| Pine wilt disease is the most important quarantine pest in the world, and it’s also the majorexotic pest and disease in China. Monochamus alternatus Hope, a longhorned beetle, is the mostcrucial carrier of this disease. So it is one of the effective method to block the transmission of thediseases by controlling the beetle. Due to the concealing habit, it is difficult to control thislonghorned by use of pesticides. So biological control is the key measure for prevention of it. Atpresent, Dastarcus helophoroides Fairmaire is a most effective natural enemy for controlling thisbeetle. Many researches have been carried out about D. helophoroides, such as the biology, theartificial breeding technology, and the it’s application technology. Up to now, some problems arestill needed to further research, for example, the artificial breeding technology is still not perfectin practical production, especially the artificial diet of larvae. In addition, the effect of the controlchanged a lot in different test, from the lowest1.69%to the highest92.42%. Based on theproblems mentioned above, researches on the larvae and the adult artificial diet of D.helophoroides are dealt with in our project and their optimization results are presented in thispaper. At the same time, the key indicators for early detection of D. helophoroides populationdegradation and its rejuvenation method are also put forward in this paper. By a large number offield tests, we proposed2kinds of maneuverability, efficient, and stable application technology,which can be used as an example for another control practices. Main reaults are as:1. D. helophoroides can be successfully breeded by larva’s artificial diet after breeding thelarvae2day with Galleria mellonella larvae. Through this method, larvae can normally developinto adults. The cocooning ratio of larvae and the eclosion ratio of adults were83.2%and78.6%respectively. When the2nd larvae were bred in the artificial diet, it took average13.4±3.6days tobegin cocooning, and44.4±7.6days eclosion. Larvae of D. helophoroides could developedhealthy, Whether they were fed by artificial diet or alive larva of M. alternatus. But the efficiencyof artificial diet was about5-8times of the alive larva. Through the orthogonal experimentaldesign we had got the best formula of artificial diet. It’s composition is as follows: Zophobasatratus powder10g, Tenebrio molitor powder10g, distilled water60mL, proline0.5g,hydroxyproline0.5g, serine0.5g, cystine1g, glucose5g, linoleic acid7g, natamycin0.5g.2. M. alternatus larvae and cricket powder, which were difficult to obtain had beeneliminated from the formula of adults artificial diet. The adults artificial diet performancedexcellently in the visual indicators, such as feed intake, adult longevity, fecundity and ratio ofhatching. The best formula of adults artificial diet are as follows: Z. atratus powder25g, T.molitor powder75g, silkworm pupa powder15g, dried yeast powder15g, glucose5g, freezedyolk5g, pine bark powder20g, sunflower seed oil30g.3. Studies on effect evaluation of artificial diet showed that were quite effective methods tobreed larvae or adults of D. helophoroidy artificial diet.The individuals of the1st,5th,10th, and15th generation of D. helophotroides were chose respectively to compare body weight, body length, cocoon time, emergence ratio, emergence time, sex ratio of larvae and body weight ofadult. there were no significant difference between individuals from artificial diet group and thatfrom alive host larvae. The1st,5th,10th, and15th generation of D. helophoroides adults fromartificial diet designed in this project also had no significant difference with control group on dietintake, body weight, body length, mating behavior and fecundity, host searching ability, parasiticability and activity index. Emergence rate, fecundity, parasitic ability and adults activity weredecreased in the20th generation. But the SOD activity decreased significantly since the15thgeneration, which can be used as a physiological index for detecting early degradation of D.helophotroides.4. The rejuvenation experimentation of D. helophoroides showed that:(1) adult emergenceratio and SOD activity returned to normal value when the degraded populations of D.helophoroides were reinoculated using natural host (M. alternatus larvae) and substitute host (Z.atratus pupae). The adult eclosion ratio reached more than70%after3generation rejuvenations;(2) although adult emergence ratio and SOD activity were increased to some degree whentreating adults in various temperature, it is difficult to recover its population viability quickly;(3)sex of wild individual determined the effect of rejuvenation, the effect of rejuvenation with wildfemale adults was better than male ones.5. Larval feeding tunnel characteristics of M. alternatus: larval feeding tunnels distributingvertically along the trunk was92.7%. The average length of larval feeding tunnel was4.8cm and2.4cm in width. More than90%oviposition pits and entrance holes were distributed in themiddle and the basal section, and less than10%distributed in the top. The number of theoviposition pit and the entrance hole of longhorned beetle in lured wood was about3-3.5times tothose of control group. It indicated that setting up the lure wood in the forest was an effectivemethod for controlling the M. alternatus.6. The efficiency and probalility of control M. alternatus by releasing D. helophoroides canbe improved by drilling holes in the lure wood. The location, depth, diameter, quantity of theholes and the quantity of D. helophoroides determined the predation ratio of the adults andthe parasitic ratio of the larvae. Hole location was the key factor and the best one was2cm abovethe feces hole. The optimal quantity and size of holes were respectively2holes per meter and0.4cm in diameter.7. The excellent effect for controlling M. alternatus can be gotten whether releasing adultsor eggs of D. helophoroides, but there was great difference on the time when the effect appeared.when host larvae density was high, releasing eggs can be used for quickly control. Pyemoteszhonghuajia carried by adults of D. helophoroides could damage the adults greatly and about30%adults died in short time. By contrast, carrying Beauveria bassiana was quite safty to D.helophoroides adults. The control effect of releasing D. helophoroides carried with pyemotes was67.6%after60days, it’s better than that releasing the pyemotes only and releasing D.helophoroides carried with B.bassiana. When releasing quantity was3D.helophoroides carriedwith B. bassiana per segment, the control effect was15.2%. The temperature had great influenceon the parasitic ratio when releasing D. helophoroides eggs, the most suitable temperature for releasing was20℃~25℃, the control ratio was up to59.4%at this temperature.8. The control effect of D. helophoroides was influenced by many factors, just as its vitality,releasing technology and other environmental conditions. Releasing D. helophoroides should suitone’s measures to local conditions, and used different control techniques according to thedifferent value of forest. For commercial forest, releasing the D. helophoroides carried withpyemotes or B. bassiana after set the lure wood which attracting large amount of beetles couldreduce the density of M. alternatus efficiently. For ecological public welfare forest,sex-pheromone attraction, releasing the D. helophoroides carried with pyemotes or B. bassianawere good measures for control M. alternatus. |
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